Graphical user interface for use with multiple electrode catheters

ABSTRACT

A graphical user interface (GUI) is provided for assisting medical personnel in interpreting data collected by a multiple electrode catheter deployed within the body. The GUI generates and displays an image of the multiple electrode catheter. By manipulating appropriate controls, the medical personnel are able to change the orientation of the displayed image until it matches the orientation of the actual multiple electrode catheter as seen on a fluoroscope. Afterwards, the medical personnel can determine the relative position and orientation of the catheter by reference to the GUI generated image. To aid in interpreting data recovered by the catheter, the individual electrodes and splines are highlighted and labeled. Electrodes recovering particular types of physiological waveforms can be automatically identified and highlighted. Comments and anatomic landmarks can be inserted where desired to further assist in interpreting data. Views from various, virtual fluoro angles can be obtained, and various images can be recorded, stored and printed. The position of a roving electrode can also be indicated.

BACKGROUND OF THE INVENTION

This invention relates generally to Graphical User Interfaces (GUIs)and, more particularly, to GUIs useful in connection with positioning,orienting and operating a multiple electrode catheter within a patient'sbody for diagnostic, therapeutic or other purposes.

Multiple electrode catheters, such as those shown and described in U.S.Pat. Nos. 5,595,183 and 5,487,391 commonly owned by the assignee hereof,are useful in a variety of medical diagnostic and therapeuticprocedures. Such catheters are particularly useful in diagnosing andtreating certain cardiac disorders, such as arrhythmias, that can occurfor example when localized areas of abnormal tissue within the heartdisrupt the normal sinus rhythm.

Today, physicians examine the propagation of electrical impulses inheart tissue to locate aberrant conductive pathways. The techniques usedto analyze these pathways, commonly called "mapping," identify regionsin the heart tissue, called foci, which can be ablated to treat thearrhythmia.

One form of conventional cardiac tissue mapping techniques uses multipleelectrodes positioned in contact with epicardial heart tissue to obtainmultiple electrograms. The physician stimulates myocardial tissue byintroducing pacing signals and visually observes the morphologies of theelectrograms recorded during pacing. The physician visually compares thepatterns of paced electrograms to those previously recorded during anarrhythmia episode to locate tissue regions appropriate for ablation.These conventional mapping techniques require invasive open heartsurgical techniques to position the electrodes on the epicardial surfaceof the heart.

Another form of conventional cardiac tissue mapping technique, calledpace mapping, uses a roving electrode in a heart chamber for pacing theheart at various endocardial locations. In searching for the VT foci,the physician must visually compare all paced electrocardiograms(recorded by twelve lead body surface electrocardiograms (ECG's)) tothose previously recorded during an induced VT. The physician mustconstantly relocate the roving electrode to a new location tosystematically map the endocardium.

These techniques are complicated and time consuming. They requirerepeated manipulation and movement of the pacing electrodes. At the sametime, they require the physician to visually assimilate and interpretthe electrocardiograms.

Multiple electrode catheters are effective in simplifying cardiacmapping and ablation procedures. Such catheters make it possible tosimultaneously obtain data from several locations within the heart orother organ using a single catheter. During such procedures, themultiple electrode catheter is introduced into a chamber of the heartusing known, minimally invasive techniques. The catheter's progressthrough the vein and into the heart can be followed on a fluoroscope.Radiopaque markers on the catheter enhance the fluoroscopic visibilityof the catheter. Once proper deployment within the heart is verified bythe fluoroscopic image, localized electrical activity within the heartis monitored by means of the individual electrodes. By noting particulartypes and patterns of abnormality in the sensed waveforms, the physicianis able to identify areas of abnormality in the heart tissue. Theabnormal tissues can then be ablated or otherwise treated to remedy thecondition.

Various advances in the catheter art now make it possible to include amultitude of individual electrodes (e.g., sixty-four individualelectrodes) in a single diagnostic or mapping electrode. It isreasonable to believe that further advances will enable still moreelectrodes to be used. However, as more and more electrodes are added,it becomes more and more difficult for the attending medical personnelto visualize and interpret the additional data that are made availableby such devices. Maximum device effectiveness is realized when theattending medical personnel are able quickly and accurately to visualizethe catheter within the body and interpret the information the device isproviding. Along with the greater resolution made possible by multipleelectrode catheters comes the need for simplified systems and methods ofdata interpretation.

In one prior data interpretation approach, the various waveformsacquired by the individual electrodes are displayed on a screen. Themedical personnel need to mentally integrate the heart activity andposition data as displayed on the recorder and fluoroscopy screens inorder to assess the health of the underlying tissue. This approachrequires a considerable degree of skill and experience on the part ofthe attending medical personnel. Furthermore, information regarding therelative location of an ablation catheter with respect to the multipleelectrodes is not readily available. More significantly, the systembecomes impractical and unwieldy as the number of electrodes increases.

In another prior approach, information acquired from a number ofsequential locations of a roving electrode is digitally sampled andcombined to construct a model "surface" that is displayed on a screenand that visually represents the tissue under consideration. Althoughmuch easier to interpret than the prior approach that required mentalintegration of various inputs, this system, too, provides an unrealisticrepresentation that requires skill and experience to use effectively.Furthermore, the surface is difficult to generate as it requires that aroving electrode be moved over the surface of the heart to reconstructits geometry point by point. To get reasonable accuracy, a high,sometimes impractical, number of points is necessary.

As the number of electrodes, and, hence, the volume of raw data,increase, it becomes more and more important to display data in a formthat can be readily interpreted and understood by the attending medicalpersonnel. Furthermore, it might be desirable to display information insuch a way that it can be easily related by the physician to informationprovided by existing visualization or imaging systems, such as afluoroscopic system. Visually based systems, which enable such personnelto "see" what is happening, offer a viable means of presenting largeamounts of data in a form that can be readily grasped and understood.Graphical user interfaces are one means by which such a goal can beachieved.

SUMMARY OF THE INVENTION

The invention provides a graphical user interface for generating avisual display depicting the relative position and orientation of amultiple electrode catheter within a body. The graphical user interfaceincludes a display screen, an image generator for generating on thedisplay screen an image of the multiple electrode catheter, and auser-actuable control coupled to the image generator for changing therelative position and orientation of the image as displayed on thedisplay screen.

It is an object of the invention to provide a new and improved apparatusfor facilitating the interpretation of data acquired through the use ofmultiple electrode catheters.

It is a further object of the invention to provide a graphic userinterface that facilitates such interpretation.

It is a further object of the invention to provide a graphical userinterface that enables medical personnel to visualize a multipleelectrode catheter in place within a body.

It is a further object of the invention to provide a graphical userinterface that can display the location of roving electrodes withrespect to the multiple electrode catheter.

It is a further object of the invention to provide a graphical userinterface that can be readily implemented on existing computerapparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the present invention which are believed to be novel areset forth with particularity in the appended claims. The invention,together with the further objects and advantages thereof, may best beunderstood by reference to the following description taken inconjunction with the accompanying drawings, wherein like referencenumerals identify like elements, and wherein:

FIG. 1 is a simplified block diagram of a cardiac diagnostic andtreatment system having a multiple electrode catheter and a GUIembodying various features of the invention.

FIG. 2 is a further simplified block diagram of the system shown in FIG.1 further including a fluoroscope for monitoring the position of themultiple electrode catheter within a patient's body.

FIG. 3 is a diagrammatic representation of a multiple electrode catheterand a system of coordinates useful in describing positions relative tothe multiple electrode catheter.

FIG. 4(a) is a flowchart diagram useful in understanding an algorithmused to rotate a wire-frame display of a multiple electrode structureusing a mouse.

FIG. 4(b) is a flowchart diagram useful in understanding the operationof an algorithm used to identify user-requested electrodes within thewire-frame display of the multiple electrode structure.

FIG. 4(c) is a flowchart diagram useful in understanding the operationof an algorithm used to associate markers or anatomical features withthe wire-frame display of the multiple electrode structure.

FIG. 5 is a sample of a display screen generated by the GUI, useful inunderstanding the look and feel thereof.

FIG. 6 is a sample of a display screen generated by the GUI showing amultiple electrode structure within the right atrium of a heart forpurposes of diagnosing and treating atrial tachycardia within the rightatrium.

FIG. 7 is a sample of a display screen generated by the GUI showing amultiple electrode structure within the left ventricle of a heart forpurposes of diagnosing and treating ventricular tachycardia within theleft ventricle.

FIG. 8 is a sample of a display screen generated by the GUI showing amultiple electrode structure within the right atrium of a heart forpurposes of diagnosing and treating atrial flutter within the rightatrium.

FIG. 9 is a sample of a display screen generated by the GUI showing thelocation of an ablation electrode during a tachycardia ablationprocedure.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2, a system 10 for diagnosing, treating orotherwise administering health care to a patient 12 using amultielectrode catheter 14 is shown. In the illustrated embodiment, thesystem 10 comprises a cardiac diagnostic system that can be used todiagnose and treat abnormal cardiac conditions, such as arrhythmias. Itwill be appreciated, however, that the system 10 is illustrative andthat the invention can be practiced in settings other than cardiac care.

As illustrated, the system 10 includes a multielectrode catheter 14deployable within the heart of the patient 12. The catheter 14, whichcan comprise a catheter of the type shown in co-pending application Ser.No. 08/587,251, filed Jan. 16, 1996, entitled Multiple Electrode SupportStructure and commonly owned by the assignee hereof, includes up tosixty-four individual electrodes 16 disposed on a plurality of splines18. Each of the electrodes 16 is connected to an individual conductor ina multiple conductor cable 20. The cable 20 terminates in one or moreconnectors through which electrical connection can be made to theindividual conductors and, hence, to the individual electrodes.

The system 10 also includes a fluoroscope 22 (FIG. 2) of knownconstruction that can be used to monitor the position of the catheter 14in the body. The fluoroscope 22 includes a head 24 that generates anddirects X-rays into the body, a sensor and an image intensifier 26 thatdetects the X-rays passing through the body, and a screen 28 thatdisplays the resulting images. The fluoroscope 22 can be rotated aroundthe patient's body to obtain views from different viewing points or"fluoro angles." Certain fluoro angles are more frequently used in thefield of fluoroscopy. FIG. 3 illustrates the viewing angles for suchviews, with respect to the coordinate system associated to thewire-frame representation of the multiple electrode structure. Theseviews are: Right-Anterior-Oblique (RAO) 30 or 45, Anterior-Posterior(AP) and Left Anterior-Oblique (LAO) 30 or 45. The AP View is providedwhen image intensifier 26 is positioned perpendicular to the patient'schest. The LAO view is provided when the image intensifier 26 ispositioned over the left side of the patient's chest. The RAO view isprovided when the image intensifier 26 is positioned over the right sideof the patient's chest. The angle with respect to the AP orientation isattached as a suffix to the LAO or RAO nomenclature (e.g. if the angleis 30 degrees the view is labeled RAO30 or LAO30). The GUI can alsoprovide virtual views from angles physically unrealized. For example,the Inferior view displays the multiple electrode structure as seen by aviewer looking horizontally from the patient's feet. The Superior viewdisplays the multiple electrode structure as seen by a viewer lookinghorizontally from the patient's head. The Left or Right 90 views areviews orthogonal to the main views AP, RAO or LAO, depending on whichview has been selected for display in the left half-screen. For example,if the left half-screen displays a LAO 30 view, Right 90 would be thecorresponding orthogonal view and equivalent to RAO 60. Similarly, Left90 would correspond to LAO 120, although this angle is not physicallyrealizable. Some fluoroscopes include a pair of heads and sensorsoriented at right angles to each other. The simultaneous orthogonalviews presented by such fluoroscopes further assist the physician infollowing the progress of the catheter into the patient's body.

The system 10 further includes a biological recorder 30 of knownconstruction that broadly functions to record, store, analyze anddisplay signals acquired by the electrodes 16 of the catheter 14. Thebiological recorder 30 includes a recording/processing unit that recordsand processes acquired signals and further includes a display unit thatdisplays the acquired signals to the attending health care personnel.

The system 10 further includes an interface 32 that enables informationacquired by the multiple electrodes to be loaded into the biologicalrecorder. To this end, the interface 32 functions broadly to coupleindividual electrodes or groups of electrodes to the biologicalrecorder. By so coupling the electrodes, it is possible to route all theacquired data into the biological recorder even though the number ofavailable inputs into the recorder may be less than the total number ofelectrodes.

The interface 32 also applies a known electrical field through theroving electrode 19 and measures the potential distribution generated atthe electrodes 16. This information is then used to estimate thelocation of the roving electrode. A system and method for determiningthe location of electrode within body has been disclosed in co-pendingapplication Ser. No. 08/745,795 Filed Nov. 8, 1996 entitled "Systems andMethods for Locating Guiding Operative Elements Within Interior BodyRegions" and application Ser. No. 08/679,156 filed Jul. 12, 1996entitled "Systems and Methods for Guiding Movable Electrode Elementswithin Multiple Electrode Structures" and commonly owned by the assigneehereof. Other methods of localizing electrodes could be employed by theskilled in the art such as presented in prior art U.S. Pat. No.5,558,091.

The interface 32 is also coupled to an external, user-actuatable,microprocessor-based computer control such as a laptop computer 34having a keyboard 36 and display screen 38. Preferably, a mouse 39 isincluded with the computer 34. The interface 32 operates under thecommand of the computer 34 to interconnect individual electrodes 16 withindividual inputs to the biological recorder 30. The Interface 32 alsocommunicates back to the computer 34 information about the location ofthe roving electrode 19. The computer 34, in turn, responds to requestsand instructions entered onto a keyboard 36 by the health care personneland commands the interface unit 32 to switch among the electrodes 16 asrequired to achieve the desired function. Commands to configure/test theunified switching system are issued by the computer 34 through thekeyboard 36.

A diagnostic and treatment system appropriate for use with the presentinvention is shown and described, for example, in U.S. application Ser.No. 08/770,971 entitled, "Unified Switching System forElectrophysiological Stimulation and Signal Recording and Analysis,"filed Dec. 12, 1996 and commonly owned by the assignee hereof, thespecification of which is incorporated by reference herein.

The computer 34 receives roving electrode location information from theinterface 32 preferably via a serial bus such as RS 232. The locationinformation can comprise three numbers indicating the 3-D coordinates ofthe roving electrode. Alternatively, it can be a data stream of 64 bitswith one bit corresponding to each of the 64 electrodes 16 of themultiple electrode structure 14. A bit equal to logic 1 indicates thatthe particular electrode 16 resides at less than a predefined distancethreshold (e.g. 2 mm) away from the roving electrode 19. A bit equal tologic 0 indicates that the particular electrode 16 resides at more thanthe predefined distance threshold away from the roving electrode 19. Assuch, the approximate location of the roving electrode 19 can beretrieved by knowing in the proximity of which of the electrodes 16 theroving electrode resides.

The invention comprises a Graphical User Interface (GUI) that isimplemented on, and resident in, the computer 34. The GUI functions toprovide the attending medical personnel with a pictorial or graphicrepresentation of the multielectrode catheter 14 within the patient'sbody. The various individual electrodes 16 and roving electrode 19 areindicated, as are their locations and orientations relative tothemselves. The representation of the multielectrode catheter 14 and/orroving electrode 19 may be manipulated on the display screen 38 until itsuggests the orientation of the catheter 14 within the patient's body12. The orientation may be guided and confirmed by comparing theappearance of the representation of the catheter 14 to the appearance ofthe catheter on the fluoroscope display 28. Such display helps "orient"the attending personnel with respect to the catheter 14 and thepatient's body 12 and thus helps them interpret the data provided by thecatheter 14.

The display of the position of the roving electrode 19 helps thephysician in guiding diagnosis or therapy application.

The invention makes use of the human ability to process information morereadily when presented in a graphic form than when presented as a seriesof numerical data points. The graphic model of the multielectrodecatheter 14 within the body 12 that the GUI provides enables theattending personnel to visualize the locations of the individualelectrodes 16 in relation to actual tissue and thus helps the personnelinterpret the data obtained by each electrode 16. The GUI furtherenables the personnel to "turn" their point of view relative to thecatheter 14 and the patient 12 and thus "see" the catheter 14 frompositions that are not physically realizable. The GUI also enables thepersonnel to label various electrodes 16, enter notes onto the display38 and otherwise add visual or informational prompts or cues thatfurther aid in interpreting the information provided by the catheter 14.

The GUI provides a graphical model that represents how a catheter 14would be situated relative to various anatomical structures if certainassumptions concerning the catheters' location are correct. By referenceto this model, the attending personnel are able to visualize were eachelectrode 16 and spline 18 is located within the patient's body 12.

During a diagnostic or other medical procedure, the fluoroscope 22 isused to monitor the position of the catheter 14. The GUI provides asimplified and idealized representation that supplements thefluoroscopic image 28.

When placed into operation, the GUI displays a simplified, idealizedgraphical image of the particular type of multielectrode catheter 14being used in the procedure. In the illustrated and preferredembodiment, the GUI provides a split screen image having a left panel 40and a right panel 42. A wire-frame image 44 of the catheter 14 appearsin standard orientations on both the right and left panels. Theparticular GUI shown and described is intended for use with a singletype of multielectrode catheter 14 of the type shown and described inU.S. Pat. No. 5,549,108 issued Aug. 27, 1996 entitled "Cardiac Mappingand Ablation Systems" and U.S. Pat. No. 5,509,419 issued Apr. 23, 1996entitled "Cardiac Mapping and Ablation Systems" and commonly owned bythe assignee hereof. Accordingly, information regarding the catheter isalready retained within the GUI. Alternatively, in other embodiments,the system operators can enter the type of catheter that is being used.The GUI can then display the type of catheter thus selected.

After the initial form of the catheter 14 is displayed, it is necessarynext, to set the view in the left panel 40 to match the view of thefluoroscope 28. To this end, the attending personnel compares thefluoroscopic image 28 of the catheter 14 and then manipulates the GUIimage 44 on the left panel 40 so that the catheter 44 shown thereonclosely matches the live view as seen on the fluoroscopic display 28. Toaccomplish this, the GUI includes a plurality of on-screen buttons 46(FIG. 3) that can be pressed to cause the catheter image 44 to rotate.These buttons are the X, Y and Z orientation buttons. These buttons areused to change the relative position of the multiple electrode catheterorientation from its initial position. Thus, the system operator movesthe cursor to one of the orientation buttons and presses the left mousebutton. This action causes the catheter image 44 to rotate about anidealized coordinate axis 48 located at the virtual multiple electrodecatheter center shown in FIG. 3. As to be expected, the X orientationbutton rotates the multiple electrode catheter image 44 in either aleft-to-right or right-to-left direction, the Y orientation buttonrotates the multiple electrode catheter image in either a top-to-bottomor bottom-to-top direction and the Z orientation button rotates themultiple electrode catheter image in either a clockwise orcounterclockwise direction.

Assume a point P₀ of coordinates x₀, y₀, z₀ on the envelope surface ofthe structure 14. After a rotation of angle α about the X axis the newposition of P(x, y, z) is given by equation (1). ##EQU1## Equation (2)and (3) define rotations of angle α about the Y and Z axis,respectively: ##EQU2##

In general, if a sequence of X, Y, or Z rotations is performed, thefinal coordinates of the point P depend on the exact order the rotationsare performed in.

Alternatively, the system operator may utilize the mouse controls torotate the multiple electrode catheter image. Whenever the cursor ispositioned in the left panel 40 and the left mouse button is pressed,the cursor changes from an arrow-style image to that of a hand-styleimage 50. This action causes the movement, that is to say, the rotationof the multiple electrode catheter image in response to the movement ofthe mouse by the system operator. By keeping the mouse left buttonpressed, the system operator may position the multiple electrodecatheter image. When the left mouse button is released, the multipleelectrode catheter image 44 remains in the current orientation. FIG.4(a) presents the flowchart of the algorithm for the mouse-drivenrotation. Element 100 draws the hand icon when the mouse button ispressed. Element 102 computes the direction of mouse movement. Based onthis information, element 104 computes two rotation angles about the Xand Y axes. Element 106 performs the actual rotation based on equations(1) and (2) above. The action of rotating the wire-frame multipleelectrode catheter representation 44 in the left panel 40 by means of X,Y and Z orientation button or mouse movement may be repeated until thesystem operator is satisfied with the orientation of the multipleelectrode catheter image in reference to the fluoroscopic image 28.

Preferably, the wire-frame representation 44 of the multiple electrodecatheter 14 shows a plurality of splines 52 corresponding in number tothe actual number of splines 18 used in the multielectrode catheter 14and further shows a plurality of electrodes 54 on each spline 52corresponding in number to the actual number of electrodes 16 on eachspline 18. In the preferred embodiment, splines 52 and electrodes 54 onthe wire-frame image 44 are highlighted, colored differently, sizeddistinctly or otherwise distinguished visually from the others toprovide a representation of the multiple electrode catheter in a virtualthree-dimensional space where the center of the wire-frame model 44 isdesignated as the center of that three-dimensional space. In theillustrated embodiment, the wire-frame image 44 is generated such thatsplines 52 and electrodes 54 which lie in the background of thethree-dimensional space (i.e., behind the center of thethree-dimensional space as viewed from the system operator's viewingangle) appear darker or shadowed compared to the splines 52 andelectrodes 54 appearing in the foreground. This enhances thethree-dimensional appearance of the multiple electrode catheter image 44on the screen 38.

Once the orientation of the virtual multiple electrode catheter image ismatched to the real fluoroscopic image, as viewed by the systemoperator, it may be saved or stored in the computer memory by pressingthe "Save View" button. The "Save View" button provides for the systemoperator to save or store the current multiple electrode catheter imageas any of the standard views, i.e., the "AP", "LAO45", "LAO30", "RAO30"OR "RAO45" views.

To further assist the operating personnel in interpreting what they see,it is frequently helpful to provide other viewing angles that arerelated to the standard fluoroscopic view but not realizable by suchequipment. To this end, the GUI based on the properly orientated imageshown in the left panel of the display, is operable to generate anddisplay multiple electrode catheter images in the right panel that areorthogonal to the view in the left panel. Such orthogonal views aredisplayed in the right panel relative to the view set in the left panel.

In the illustrated embodiment, the GUI provides orthogonal viewscalculated from the "Superior", "Inferior", "Left 90" and "Right 90"views.

Preferably, the wire-frame representation 44 of the multiple electrodecatheter 14 shows a plurality of splines 52 corresponding in number tothe actual number of splines 18 used in the multielectrode catheter 14and further shows a plurality of electrodes 54 on each spline 52corresponding in number to the actual number of electrodes 16 on eachspline 18. Preferably, one or more of the splines 52 or electrodes 54 ishighlighted or otherwise distinguished visually from the others toprovide a reference for orienting the displayed wire-frame image 44. Inthe actual catheter 14, one or more of the splines 18 or electrodes 16are provided with a fluoroscopic marker that appears on the fluoroscopescreen 28 and that serves to identify a particular one of the electrodes16 for reference purposes. The electrode 60 highlighted by the GUIcorresponds to this electrode and is positioned to closely match theposition of the corresponding electrode on the fluoroscope screen 28.

The described procedure thus coordinates the "three dimensional"wire-frame multiple electrode catheter representation 44 generated anddisplayed by the GUI with the two dimensional display of the actualmultiple electrode catheter 14 shown on the fluoroscope screen 28.

After the displayed multiple electrode catheter image 44 is properlyoriented, the view can be saved by clicking the "Save View" and "OK"buttons that appear on the display screen 38.

In the illustrated embodiment, the wire-frame image 44 generated on theleft panel 40 of the display 38 corresponds to the view of the multipleelectrode catheter 14 displayed on the fluoroscope screen 28. To furtherassist the operating personnel in interpreting what they see, it isfrequently helpful to provide other views that are not easily realizableusing the fluoroscopic equipment 22. To this end, the GUI, based on theproperly oriented image 44 shown on the left panel 40 of the display 38,is operable to generate and display images 44' of how the multipleelectrode catheter image 44 would appear if view from other angles. Suchalternate views are displayed on the right panel 42 of the display 38.

In the illustrated embodiment, the GUI provides "Superior," "Inferior,""Left 90°" and "Right 90°" views. These views are obtained by clickingthe appropriately labeled corresponding buttons on the screen 38. Theimage appearing on the right panel 42 of the display 38 tracks theorientation of the image 44 on the left panel 40. Thus, if the imageorientation on the left display panel 40 is changed or adjusted, theright image 44' will also change to reflect the new orientation of thecatheter 14 relative to the body.

In the illustrated embodiment, fluoro angles between -90° and +90° canbe used and can be entered into the GUI. Thus, the GUI can be still beeffectively used if, for some reason, the attending personnel elect toposition the fluoroscope to a non-standard fluoro angle. In theillustrated embodiment, views at the standard fluoro angles of -45°,-30°, 0°, +30° and +45° can be automatically saved. Customized views atnon-standard fluoro angles can also be named and saved.

As previously mentioned, the primary function of the GUI is to provide avisual image or model 44 that assists the operating personnel invisualizing the multiple electrode catheter 14 within the patient's body12 and interpreting the data acquired from the multiple electrodecatheter 14. Although this is largely achieved by orienting thewire-frame display representation of the electrode basket to match theactual image provided by the fluoroscope, the GUI provides severaladditional functions that further enhance its effectiveness. Various ofthese additional functions are described below.

A MARKERS function is provided which enables the operator to alter andenhance the displayed multiple electrode catheter wire frame image. TheMARKERS function includes an ADD MARKER function that enables theoperator to add an identifier or marker to selected locations of theelectrode image 44 displayed in the left screen 40. This function isuseful if the operator wishes to mark selected locations that aresignificant or of interest, such as mapping sites, ablation sites, etc.By having such sites highlighted or otherwise distinguished, theoperator is better able to remain coordinated and oriented with thedisplayed image and, therefore, better able to interpret data recoveredby the multiple electrode structure. The markers appear on the surfacedefined by the various splines 52.

The MARKERS function is used by clicking the ADD MARKER button thatappears on the screen after the general "MARKERS" button is clicked.Pressing the right mouse button on an electrode causes a marker toappear on the screen. With the right button thus depressed, the mouse isused to "drag" the marker over the implied surface of the multipleelectrode catheter to the desired location. When the right button isreleased, the marker is "dropped" into the desired marker location.Markers can thus be placed near electrodes on either the foreground orbackground of the multiple electrode catheter. FIG. 4(b) shows theflowchart of the algorithm used to add markers. Element 200 assigns theinitial x₀, y₀, z₀ coordinates of the marker when the mouse button ispressed. These initial coordinates are identical to those of theelectrode 16 acting as origin of the placement. Element 202 generatesthe marker symbol and inserts the corresponding software data structureinto a linked list. Element 204 computes the direction of the mousemovement based on information received from the mouse port. Element 206converts the direction information into two rotation angles, about the Xand Y axes, respectively. Element 208 computes the new location of themarker based on equations (1) and (2). Element 210 assigns the final x,y, z coordinates to the marker when the mouse button is released.Markers are created as data structures comprising: pointer to previousmarker, order number, coordinates, comments, time stamp and pointer tonext marker.

Also included in the MARKERS function is a COMMENT function that enablesthe operator to add custom notes or comments to each marker. Forexample, if the operator wishes to comment on the significance of eachselected, marked site, the COMMENT function can be used for thispurpose. A COMMENT window appears as soon as the marker is "dropped" atthe selected site. A time stamp is preferably included in the comment.The operator can enter the desired comment into the comment window usingthe computer keyboard. By clicking the OK button, the comment thusentered is saved. If no comment is desired, the CANCEL button can beclicked. A PREV. COMMENT button is provided which, when actuated,displays comments previously entered with earlier markers. A NEXTCOMMENT button displays comments associated with later entered markers.Once a marker is "dropped," its comments can be retrieved by placing thecursor onto the marker and pressing the right mouse button.

A DELETE MARKER function is provided for deleting previously enteredmarkers. This function is actuated by clicking on the DELETE MARKERbutton and thereafter placing the cursor on the desired marker. When theright mouse button is pressed, the selected marker is deleted. When aDELETE operation is performed the corresponding marker data structure isremoved from the linked list by employing well-known data structuresoftware techniques.

The MARKERS function is terminated by clicking the CLOSE button.

The GUI also provides a mapping function that enables the operator tocreate any of five types of binary maps. The available mapping functionsare (1) EARLY ACTIVATION, (2) FRACTIONATION, (3) GOOD PACE MAP, (4)CONCEALED ENTRAINMENT and (5) USER DEFINED and are characterized asfollows:

EARLY ACTIVATION. The EARLY ACTIVATION mapping function identifies andmarks the electrodes where early depolarization of the heart tissue hasoccurred. Early depolarization is often an indicator of abnormal hearttissue adjacent the electrode.

FRACTIONATION. The FRACTIONATION mapping function identifies and marksthe electrodes where the electrograms sensed by such electrodes appearfractionated or broken in appearance. Again, the existence offractionated electrograms a particular electrode site is often anindicator of abnormal cardiac tissue at that site.

GOOD PACE MAP. The GOOD PACE MAP mapping function identifies and marksthe electrodes with high pace mapping matching index. This indexreflects how many of the morphologies of 12-lead surfaceelectrocardiograms (ECG) acquired during non-induced arrhythmia matchthe morphologies of the same signals acquired during paced inducedarrhythmia from the particular electrode. If by pacing from a particularelectrode 16, a high number of the 12-lead ECG morphologies are similarduring non-induced and pace-induced arrhythmia then it is likely thatthe particular electrode 16 resides close to an arrhythmogenic focus.

CONCEALED ENTRAINMENT. The CONCEALED ENTRAINMENT mapping functionidentifies and marks the electrodes where arrhythmia entrainment wasachieved. Abnormal cardiac tissue often is located electrodes exhibitingCONCEALED ENTRAINMENT.

USER DEFINED. The USER DEFINED mapping function enables the user tospecify particular criteria to be used for categorizing signals obtainedby the multiple electrodes. Electrodes providing signals meeting theselected criteria are identified and marked. The USER DEFINED mappingfunction allows the physician to locate areas of cardiac tissueexhibiting certain preselected characteristics and further enhances thediagnostic function of the system.

The various mapping functions are of importance in identifying potentialablation sites. Frequently, abnormal cardiac tissue, which can beeffectively treated through ablation, often exhibits more than oneabnormal characteristic. Such sites frequently appear on two or more ofthe EARLY ACTIVATION, FRACTIONATION and CONCEALED ENTRAINMENT maps. Ifthe same electrode or groups of electrodes appear on two or more of theACTIVATION, FRACTIONATION, GOOD PACE MAP and CONCEALED ENTRAINMENT maps,a likely site for ablation is particularly well indicated.

Numeric values, such as activation time numbers, cardiac signalvoltages, or propagation velocities, can be associated to each electrodeof the multielectrode catheter structure. Then, isovalues (i.e.,isochronal, isopotential, isoconduction etc.) can be generated. Theiso-value maps can be used in association with the binary maps, markersand anatomic features to further identify potential ablation sites.

The mapping function is initiated by clicking the CREATE MAP button thatappears on the display screen. When this button is clicked, a popupwindow appears offering a choice of any of the five mapping functions.By clicking on the selected choice, the desired mapping function isinitiated.

After the desired mapping function is selected, the mouse is used todrop binary map markers at the electrodes of interest. This is done bymoving the mouse to place the cursor over the electrode of interest andthen depressing the right mouse button to drop the marker at theselected electrode. The algorithm for generating binary map markers issubstantially similar to that shown in FIG. 4(b). The only difference isthat the rotation step 208 is not performed. The binary map markers aredirectly attached to the selected electrode 16. Similar data structuretechniques are used to create and update the required binary map linkedlists. The data structure corresponding to a binary map markercomprises: pointer to previous marker, electrode number, binary maptype, comment, time stamp, iso-value type and pointer to next marker.After the selected electrodes are thus marked, a different type ofbinary map can be selected or the CLOSE button appearing on the pop-upwindow can be clicked. Specific comments can be entered by the operatorusing the computer keyboard. If the comments are acceptable, the OKbutton is then clicked. If not, the CANCEL button is clicked and thecomments are not saved. Comments can later be retrieved by placing thecursor over a binary map marker and then pressing the right mousebutton.

Various other functions are provided in connection with the mappingfunction. A SHOW MAP function can be selected by clicking the SHOW MAPbutton. This function displays the types of binary maps that areavailable. By clicking on one of the listed types, the selected binarymap will then be displayed. The types of maps being displayed will beindicated with a check mark (.check mark.).

A CLEAR MAPS button functions, when clicked, to delete and clear allexisting binary maps.

A REMOVE MAP POINTS button operates, when clicked, to clear a specificmap point by placing the cursor on the map point to be removed andclicking the right mouse button.

A CLOSE button functions, when clicked, to close the BINARY MAPfunction.

Still additional functions are provided by the GUI.

A FEATURES function displays a pop-up window with choices for anatomicmarkers. The anatomic markers function to indicate on the display thelocation of certain anatomic structures or landmarks (e.g., the aorticvalve, the inferior vena cava, the superior vena cava etc.) relative tothe multiple electrode catheter. Having the relative locations of suchanatomical structures displayed relative to the multiple electrodecatheter and its other features helps the physician in guiding thecatheter, and in mapping and treating the cardiac tissue.

To operate this function, the FEATURES button is clicked, which causes apop-up window to be displayed. The window displays a number of choicesfor anatomic markers. The desired anatomic marker is selected using thecursor, and the marker is then dragged to the desired location using theright button of the mouse. At the desired location, the right mousebutton is released to drop the marker at the desired location. Thealgorithm which inserts these anatomic markers works similarly to thatshown in FIG. 4(b). However, the anatomic markers are not created aslinked lists data structures. The anatomic markers can be deleted as agroup by clicking on the CLEAR ALL FEATURES button, or can beselectively deleted by clicking the REMOVE FEATURE button.

A PRINT function can be selected by clicking on the PRINT button. Thisfunction prints both multiple electrode catheter views plus current andexisting comments on the system's default printer.

A SAVE VIEW function saves the selected principal view (i.e., the leftscreen panel) when actuated. All other views are updated accordingly.

A SHOW SPLINES function labels the individual splines of the electrodebasket when actuated. This button also turns into HIDE SPLINES tofacilitate label removal when desired. Spline labels in the foregroundappear brighter than spline labels in the background to further enhancethe three-dimensional effect provided by the GUI.

A FIND SITE function operates, when actuated, to enable the operatorquickly to locate a particular electrode. When this function isactuated, the operator enters the designated electrode onto the keyboardand the GUI then highlights the electrode thus selected. In theillustrated embodiment, a circle is flashed around the selectedelectrode until a next action is taken. FIG. 4(c) illustrates theflowchart of the algorithm that implements the Find Site function.Element 300 accepts a user-entered electrode number (e.g. A4, D3) andreturns an entry to a 8×8 matrix associated to the electrodes 16 onstructure 14. Element 302 accepts as input the matrix entry and returnsthe x, y, z coordinates of the user-selected electrode 16. Element 304draws and flashes a circle around the x, y, z coordinates received fromelement 302. Element 304 also checks whether any other action is issuedby the computer 34. If the answer is yes then it stops the Find Sitefunction and returns to normal screen.

A ZOOM VIEW L function operates, when actuated, to expand the lefthalf-screen to a full screen view.

A ZOOM VIEW R function operates, when actuated, to expand the righthalf-screen to a full screen view.

A RESET function operates to reset the screen to a default view whenactuated.

Various examples of the GUI in use are shown in FIGS. 6, 7, 8 and 9.

FIG. 6 represents the multiple electrode structure within the rightatrium of the heart. Display panel 40 shows the wire frame image 44 fromthe AP view, while the right panel 42 shows the image 44' from theinferior view. The relative locations of the Superior Vena Cava andInferior Vena Cava are marked "SVC" and "IVC" respectively on thedisplays. A first early activation site is indicated by the marker ♦1,while a second early activation site is indicated by the marker ♦2. Theuser-entered legend under the display indicates that the first site wasablated at time 09:42:36, while the second site was ablated at time09:43:02. The legend further indicates that the detected arrhythmia wasrendered noninducible following such ablation, thereby indicating asuccessful treatment.

FIG. 7 represents the multiple electrode structure within the leftventricle for treatment of left ventricular tachycardia. In FIG. 7, theview in the left display panel 40 is from the AP position, while theview in the right panel 42 is from the RAO 45 position. In this example,the various binary mapping functions have been used, and two sitessatisfying two or more of the selection criteria have been located andindicated by the symbols ♦, , and ★. In particular, two sitesexhibiting fractionation and concealed entrainment have been located andidentified. Such sites are likely candidates for tissue ablation.

FIG. 8 represents the multiple electrode structure within the rightatrium for treatment of atrial flutter. The view in the left panel 40 isfrom the AP position, while the view in the right panel is from the LFT90 position. Three markers, ♦1, ♦2, and ♦3 are shown in both views.According to the user-entered legend, these markers indicate first,second and third atrial flutter ablation points, respectively.

FIG. 9 depicts the GUI being used to guide the roving electrode 19. Theview in the left panel 40 is from the AP position, while the view in theright panel 42 is from the SUPERIOR position. The relative position ofthe roving electrode is indicated by the elongate symbol. Thehighlighted symbols * adjacent the electrodes C6 and C7 indicate earlyactivation sites. The user-entered legend indicates a potentialtachycardia ablation site between these electrodes.

The GUI is preferably configured to operate on WINDOWS® compatiblelaptop or desktop computers. Preferably, the computer should include a486DX or higher processor operating at a clock frequency of 66 MHZ orhigher. A hard disk capacity of 360 MB, and a main memory capacity of 4MB should be available. Preferably, the GUI is configured to run onWINDOWS® 3.1, WINDOWS 95® or NT operating systems. The GUI is preferablyrealized as a "C" language program created using known programmingtechniques.

While a particular embodiment of the invention has been shown anddescribed, it will be obvious to those skilled in the art that changesand modifications can be made without departing from the invention inits broader aspects, and, therefore, the aim in the appended claims isto cover all such changes and modifications as fall within the truespirit and scope of the invention.

We claim:
 1. A graphical user interface for generating a visual displaydepicting a multiple electrode catheter and its relative position andorientation within a body, comprising:a display screen; an imagegenerator for generating on the display screen an image of the multipleelectrode catheter; and a user-actuable control coupled to the imagegenerator for changing the relative position and orientation of theimage as displayed on the display screen to allow for the display of theimage from physically unrealized angles.
 2. A graphical user interfaceas defined in claim 1 wherein the user-actuable control further operatesto display the image from one or more predetermined viewing angles.
 3. Agraphical user interface as defined in claim 1 wherein the imagegenerator highlights selected electrodes on the displayed image of themultiple electrode catheter.
 4. A graphical user interface as defined inclaim 1 wherein the multiple electrode catheter includes a plurality ofsplines and the image generator function to highlight selected splinesof the displayed image.
 5. A graphical user interface as defined inclaim 1 wherein the image generator displays certain elements of theimage at brighter intensity than other elements of the image to enhancethe three-dimensional appearance of the displayed image.
 6. A graphicaluser interface as defined in claim 1 wherein the image generator furthergenerates labels associated with at least one electrode of the multipleelectrode catheter.
 7. A graphical user interface as defined in claim 1wherein the image generator further generates labels associated with atleast one spline of the multiple electrode catheter.
 8. A graphical userinterface as defined in claim 1 wherein the image generator furthergenerates a label associated with a roving electrode.
 9. A graphicaluser interface as defined in claim 1 wherein the image generator furthergenerates anatomic markers representative of anatomic features withinthe body.
 10. A graphical user interface as defined in claim 1 whereinthe image generator further generates user-created markersrepresentative of preidentified events occurring during anelectrophysiological procedure.
 11. A graphical user interface asdefined in claim 1 wherein the user-actuable control is operable toplace the anatomic markers at user-selected locations relative to thedisplayed image.
 12. A graphical user interface as defined in claim 1wherein the image generator further operates to develop iso-value mapsin response to physiological data received by individual ones of theelectrodes of the multiple electrode catheter.
 13. A graphical userinterface as defined in claim 1 wherein the image generator displays theposition of roving electrodes with respect to the multiple electrodecatheter.
 14. A graphical user interface as defined in claim 1 whereinthe user-actuable control includes the keyboard of a computer.
 15. Agraphical user interface as defined in claim 1 wherein the graphicaluser interface comprises a computer and a software program operating onthe computer.
 16. A graphical user interface for generating a visualdisplay depicting a multiple electrode catheter and its relativeposition and orientation within a body comprising:a display screen; animage generator for generating on the display screen an image of themultiple electrode catheter, wherein the image generator operates todevelop binary maps in response to physiological data received byindividual ones of the electrodes of the multiple electrode catheter;and a user-actuable control coupled to the image generator for changingthe relative position and orientation of the image as displayed on thedisplay screen.
 17. A graphical user interface as defined in claim 16wherein the binary maps are based on the detection of early activationoccurrences at one or more electrodes of the multiple electrodecatheter.
 18. A graphical user interface as defined in claim 16 whereinthe binary maps are based on the detection of fractionation occurrencesat one or more electrodes of the multiple electrode catheter.
 19. Agraphical user interface as defined in claim 16 wherein the binary mapsare based on the detection of good pace occurrences at one or moreelectrodes of the multiple electrode catheter.
 20. A graphical userinterface as defined in claim 16 wherein the binary maps are based onthe detection of concealed entrainment occurrences at one or moreelectrodes of the multiple electrode catheter.
 21. A method of utilizinga multiple electrode structure within a body comprising:locating themultiple electrode structure within a body, displaying the actualmultiple electrode structure on an imaging screen, generating anddisplaying on a second screen an image representing the multipleelectrode structure, and changing the displayed orientation of the imageuntil the orientation of the displayed image substantially matches theorientation of the actual multiple electrode structure as displayed onthe imaging screen.
 22. A method as defined in claim 21, furthercomprisingintroducing a roving electrode into the body, and generatingand displaying an image representing the roving electrode on the secondscreen.
 23. A method of utilizing a multiple electrode structure withina body comprising:locating the multiple electrode structure within abody, displaying the actual multiple electrode structure on an imagingscreen, generating and displaying on a second screen an imagerepresenting the multiple electrode structure, changing the displayedorientation of the image until the orientation of the displayed imagesubstantially matches the orientation of the actual multiple electrodestructure as displayed on the imaging screen, and generating anddisplaying on the second screen binary maps indicative of the presenceor absence of predetermined physiological events.
 24. A method asdefined in claim 23 comprising the further step of generating two ormore binary maps representative of the presence or absence of two ormore different predetermined physiological events.
 25. A method asdefined in claim 24 comprising the further step of identifying potentialtreatment sites by correlating the occurrence of two or more differentphysiological events at single locations.